<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
<p>点击按钮，在等待 3 秒后弹出 "Hello"。</p>
<button onclick="myFunction">点击我</button>
</body>
</html>
<script>

function myFunction(){
	setTimeout(function(){alert("Hello")},3000);
}


</script>